workaround for Cygwin, to make it work in the important special case without extra files;

--- a/src/Pure/PIDE/document.ML	Tue Aug 16 22:48:31 2011 +0200
+++ b/src/Pure/PIDE/document.ML	Tue Aug 16 23:17:26 2011 +0200
@@ -340,8 +340,9 @@
                   let
                     val (thy_name, imports, uses) = Exn.release (get_header node);
                     (* FIXME provide files via Scala layer *)
-                    val dir = Path.dir (Path.explode name);
-                    val files = map (apfst Path.explode) uses;
+                    val (dir, files) =
+                      if ML_System.platform_is_cygwin then (Path.current, [])
+                      else (Path.dir (Path.explode name), map (apfst Path.explode) uses);
 
                     val parents =
                       imports |> map (fn import =>